The invention relates to a double T-shaped steel piling wall profile.
Double T-shaped piling wall profiles are known, for example, as Peiner steel piling walls (see, for example, section of the delivery program “Hoesch Stahlspundwände” January 2003 [“Hoesch Steel Piling Walls”] and/or “Peiner Stahlspundwände” March 2002 [“Peiner Steel Piling Walls”], available from HSP Hoesch Spundwand und Profil GmbH, Dortmund, Germany).
These company brochures describe hot-rolled piling wall profiles with two flange sections which are connected in the center by a web. Club-shaped connecting end sections adapted to receive interlocks adjoin the flange sections. The flange sections are oriented at least on the outside essentially horizontally. The inside of the flange can have a wedge-shaped taper from the flange center to the flange end, or can, like the outside of the flange, extend essentially horizontally.
The input stock for these piling wall profiles produced by hot rolling is in the form of either slabs, blocks or so-called beam blanks, wherein the latter are cast with a cross-section that is close to the final dimensions.
When using a heated slab or a block, the essentially rectangular cross-section is transformed in a shaping mill into a shape that is close to the final dimensions of the double-T profile, and subsequently rolled to the desired final dimension in a finishing mill stage, which includes at least a universal mill and an edger. When using the beam blanks, blooming can be limited to a few reduction passes, because the dimensions of the cast cross-section are already close to the final dimensions.
The finishing mill stage consists of a roller set for machining the outside and the inside of the rough profile.
The double T-shaped piling walls are used, for example, for supporting sudden height changes in the terrain and for shoring up trenches and port facilities. The piling wall profiles must be able to withstand large horizontal forces which cause a corresponding bending load of the piling walls perpendicular to the piling wall wall. The dimensions are typically determined by the bending load which the piling wall profile must be able to absorb from the lateral earth and/or water pressure via the section modulus.
Depending on the load to be absorbed, the piling wall profiles can be connected via the interlocks either with one another, thereby producing a closed wall from individual support elements with a high section modulus, or the piling wall profiles can be used as a mixed piling wall, whereby for example U-shaped or Z-shaped fill elements are connected by the interlock to the double T-shaped profile. In the latter case, only the double T-shaped profiles function as support elements, whereas the fill elements essentially only perform a sealing function.
Double T-shaped piling wall profiles are offered essentially in different lengths and with flange sections having different wall thicknesses, depending on the required section modulus.
The club-shaped connecting end sections of the flange typically have a standard geometry, so that all standard profiles can be connected with each other or in combination with other profiles by using a single interlock.
The commercially available standard piling wall profiles frequently do not satisfy the section moduli required by a static design. For example, a standard delivery program of a company may not be able to deliver a piling wall profile with a required section modulus, or the required section modulus may fall between two available standard piling wall profiles.
If the required section modulus falls between two available standard piling wall profiles, then it makes often no economic sense to select the next larger profile which may be significantly more expensive. If a standard delivery program is unable to supply the required section modulus, then a completely new piling wall profile may have to be produced.
For producing a new piling wall profile by hot rolling, an expensive roller set must be procured at least for the finishing mill stage, and a large inventory may be required and expensive rolling tests, until a high-quality product is ready for sale.
The present technology offers various possibilities for increasing the section modulus of a standard profile, without having to either select an uneconomical profile or to produce an entirely new profile with a different geometry (essentially related to the overall height and the flange thickness), which would be a complex and expensive process.
To eliminate these disadvantages, attempts have been made to increase the section modulus according to the customer requirements while maintaining the geometry of the standard profile.
In one embodiment, which has been used and proven effective in practice, steel lamellae have been welded to one or both exterior flange surfaces of the piling wall profile (see excerpts from the delivery program “Peiner Stahlspundwände” March 2002) [“Peiner Steel Piling Walls”]. These lamellae are preferably arranged in the region of the highest bending moment.
Welding these lamellae is expensive and adds costs, because the piling wall profile must be straightened due to the welding stress.
In another approach, the section modulus of a standard profile can be increased to attain a greater average wall thickness in the flange by moving the finishing rollers apart during the rolling process (see excerpts from the delivery program “Hoesch Stahlspundwände” January 2003 or “Peiner Stahlspundwände” March 2002).
The flange thickness of wedge-shaped flange sections is given as an average value which corresponds to the cross-sectional area of the flange divided by the overall width of the profile. The average wall thickness of profiles with parallel flanges corresponds to the nominal wall thickness in the flange section.
The size of the opening between the outside rollers of the finishing roller stage which determines the average flange thickness is increased by a value in the range of millimeters, which increases the overall height of the profile and hence also the average wall thickness of the flange.
Disadvantageously, the pass of the outer rollers also enlarges the club-shaped geometry of the connecting end section, in addition to increasing the average flange thickness.
The tolerances in the connecting region are relatively tight to enable the club-shaped section to securely engage with the standard interlock to withstand the load on the piling wall. If the average wall thickness increases too much, then the dimension of the club-shaped section would also increase to a point where the standard interlock can no longer be pushed over the club-shaped section.
With this approach, new interlocks would have to be produced which can be quite expensive.
It is therefore an object of the invention to provide a piling wall profile which can overcome the aforedescribed disadvantages of conventional profiles.